1. Field of the Invention
The present invention relates to a linear motion rolling guide unit in which almost all of the component parts are made of what is called high performance engineering plastic resin which is excellent in heat resistance, chemical resistance, and mechanical and physical strengths and, more particularly, to a linear motion rolling guide unit which can effectively be used even in special operational environments, for instance, under severe mechanical and chemical conditions encountering with manufacturing of chemicals, in the vacuum or water such as sea water, and the like.
2. Description of the Related Background Art
In a conventional linear motion rolling guide unit, only limited component parts, for instance, side plates which are attached to both ends in the longitudinal direction of a casing are made of a resin such as POM (polyoxymethylene), PBT, PES, or the like and the other component parts which require a high mechanical strength in operation are made of steel or iron. However, in recent years, various kinds of resins having physical and mechanical strength substantially equal to that of steel have been developed. There has been proposed by the same applicant that the above-mentioned new resinous materials can be used in place of steel from which the conventional parts have been made (Japanese Patent Application No. 211364-1989).
According to the linear motion rolling guide unit made from resin as disclosed in Japanese Patent Application No. 211364-1989, the direction turning passages, return passages, and track surfaces can be easily and accurately positioned so that the slide resistance of the rolling members when they run along the endless ball circulating passages is made small to the maximum extent.
As compared with the unit made of steel, elastic deformation rate is made large, weight is made small, aligning performance is made high, and unit as a whole can withstand severe mechanical and chemical operating conditions.
However, the above-mentioned prior unit has a poor selectivity in operative applications.
Namely, the prior unit has the following disadvantages:
(1) The direction turning passages for rolling members are provided outside the casing body, therefore a pair of side plates are necessary to provide said passages,
(2) The rolling circuit planes in the casing defined by the respective endless circulating passages for rolling members which are provided in laterally symmetrical relation with each other in the casing are designed to be positioned at the same level as the corresponding load bearing, casing side track grooves.
(3) The fastening of the side plates onto the longitudinally opposing end wall surfaces of the casing is limited to the so-called snap-fitting engagement consisting of a cylindrical male projection and a projection-receiving female hole mating therewith,
(4) The roller members are limited only to balls, and
(5) The number of load bearing track grooves between casing and track rail is limited to only two.
The present invention is to provide a linear motion rolling guide unit for aiming at expanding the above-mentioned selectivity in operative applications, thus enabling to meet a wide range of utility.
The improvements brought about by the present invention are as follows:
(1) The direction turning passages for rolling members are provided even within the casing body, therefore any side plates employed in the prior art unit can be eliminated,
(2) The rolling circuit planes in the casing defined by the laterally the respective endless circulating passages for rolling members may be positioned, as seen in the cross section of the casing, at a desired angle relative to the centrally and longitudinally vertical plane of the rail track on which the casing straddles. Namely, the rolling circuit planes can be positioned horizontally flat or inclined, as seen in the cross section of the casing, in the desired degree and in any direction, viz., downward or upward direction.
(3) The casing body may be assembled from a plurality of portions consisting of a flat deck-shaped portion and a pair of leg-forming portions to form the endless circulating passages for rolling members.
(4) The fastening of the casing body with a pair of side plates, if used, is selectively carried out by either using a combination of a cylindrical projection provided on one part, a projection-receiving hole provided on the other with or without adhesive agent being applied therebetween upon the mating thereof,
(5) in place of bearing balls, use may also be made of rollers that are cheaper than balls in manufacture, and,
(6) The number of load bearing track grooves provided between the casing and the rail track may be increased as necessary, such as for example, two rows on one side of the track rail with the corresponding rows on the other side of the casing so that not only a four track-type unit but any multitrack units may also be realized according to the present invention.